Start from the event, not the tub
If a Whirlpool dishwasher stopped draining on a day you can name, the plumbing around it is the place to start. A new disposer arrives with its dishwasher inlet blanked off. Sink work disturbs the high loop or the air gap. A reinstall kinks the drain hose behind the cabinet where nobody can see it. A long gap in use lets debris dry hard in the sump. All four are cheaper to check than a pump, and none of them is a fault in the machine.
What you are seeing
- Draining stopped on a day you can name.
- It stopped after a disposer was fitted or replaced.
- It stopped after plumbing work under the sink.
- It stopped after the machine was pulled out and refitted.
- Not this fault: Drainage that has slowly got worse over months has no single event - use the symptom page.
- Not this fault: Water on the floor rather than in the tub is a leak, and a different page.
Most likely causes, ranked by history
- New disposer fitted with the knockout plug still in place — Why ranked: First because it removes the drain route entirely, and it is the single most common cause of a drainage fault that begins on a known date.
- Sink work removed the high loop or blocked the air gap — Why ranked: Second because it explains water siphoning back into a tub that had already emptied - the version that comes and goes.
- Drain hose kinked during a reinstall — Why ranked: Ranked here because it is invisible from the front and dates precisely to the day the machine was moved.
- Debris dried hard in the filter and sump during a gap in use — Why ranked: It explains a machine that drained perfectly before a holiday and not afterwards, which nothing above it does.
- A pump failure that coincided with the event — Why ranked: Last, because a coincidence is possible but far rarer than the four events above.
What to check, in order
- Write down when draining stopped and what was done that week. — Because: The whole method here depends on getting the history straight before any check.
- Ask whether a disposer was fitted, and whether the inlet plug was removed. — Because: Rank one is settled by that answer alone.
- Look under the sink for a high loop and lift the air gap cap. — Because: Rank two is visible and both are correctable without tools.
- Reach behind the cabinet and follow the drain hose for a kink. — Because: Rank three cannot be seen from the front and dates to the reinstall.
Checks you can do safely
- Write down the date draining stopped and any disposer, plumbing or reinstall work near it. — N: 1 — Tools: Notepad — Time: quick
- Look under the sink and confirm the drain hose rises into a high loop and is not kinked anywhere you can reach. — N: 2 — Tools: Torch — Time: moderate
- Lift the air gap cap on the sink top and clear any debris inside it. — N: 3 — Tools: Gloves — Time: quick
- Twist out the tub filter, rinse it and clear any dried debris from the sump by hand. — N: 4 — Tools: Gloves — Time: moderate
- Stop rule: Stop here. Clearing the disposer inlet, disconnecting the drain line or removing the pump cover is plumbing or service work.
Before you reach into the tub
Safety
Switch off the dishwasher breaker before reaching into the sump, and never put a hand into a disposer. A capacitor can hold a charge after the power is off. The water in a tub can still be hot at the end of a cycle. Broken glass in the sump is common; use gloves and a torch. Never run the machine to test while the pump cover is off.
When this becomes a service call
The machine has not drained since a disposer was fitted. Water stays with the hose, the loop and the air gap all confirmed clear. A rattle or grind comes from the pump. No event explains the timing - then work from the symptom page instead.
Nearest pages
What this page does not cover
This is generalized information for Whirlpool dishwashers as a group, ranked by what changed rather than by the symptom. It does not name parts. If no event explains the timing, use the symptom-ranked page below.
Links down: - [Whirlpool Dishwasher: Will Not Drain](/blog/whirlpool-dishwasher-drainage-failure)
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
